In a virtual-object collaborative environment, remote collaborators can interact with and modify a shared virtual object. The shared virtual object can be in the form of visible images, instances of which are presented locally to respective collaborators. Interactions with the virtual object can be effected using human input devices. For example, the virtual object can be a virtual document page; a collaborator can annotate the virtual document page using an IR pen (a stylus with a tip that emits infra-red light). The annotations can then be presented to remote collaborators. In other words, the images of the document pages at the different locations can be reconciled to the effect that they all represent the same object.